Widest Tires on our 18"

[LIVEVIL]

I am wondering what the widest tires we can fit on our stock 18" wheels, if I also have and Eibach drop? I am only concerened about the rear wheels and everything rubbing with a larger size. I have found in searching many different answers but nothign for sure. Lots of 245 sizes mentioned, but even that doesn't seem wide enough.

[LIVEVIL]

I plan on keeping the front tires the same 235/40/18 size. I have seen people saying they can run 265/275 in the rear with no rub. I am just wondering with the drop, will I get rub?

[LIVEVIL]

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
235/40-18 3.7in 12.7in 25.4in 79.8in 794 0.0%
255/35-18 3.5in 12.5in 25.0in 78.6in 806 -1.5%

How does this stack up?

[MC2182]

Check out what the aussie guys are saying on their forum http://www.ls1.com.au. The general consensus is that 255 or 265 is too wide for an 8" rim. In aussie land you can even lose your insurance if you spec a tire that is too large for your rim.

255 - 275 will fit in the rear but you possibly have stability issues as the sidewall will distort.

Before I started reading threads there I was dead set on a 255 or 265 rear but the unfortunate thing is, with an 8" rim you will never be able to effectively use that contact patch thus negating any benefits of going wider.

I'm going to go 245/40R 18's all around with Potenza RE050 Rubber, seems like a good combination to me until I decide to get new wheels.

[LIVEVIL]

hmmm, making me rethink the 255's now.

[LIVEVIL]

http://www.ls2gto.com/forums/showthread.php?t=6395 7

Just saw that thread and I like the way those 265's look. I am guessing my 255's can't be that bad then.

I guess 265 are better though.

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
235/40-18 3.7in 12.7in 25.4in 79.8in 794 0.0%
265/35-18 3.7in 12.7in 25.3in 79.5in 797 -0.4%

[MC2182]

I agree, those look badass but I believe they are an 8.5" Rear rim thus making 265's not so horrible out back.

I think you are correct in stating the correct match for the rear stagger is a 265/35R18. My boss has a Maserati and the fronts are 235/40/18 and rears are 265/35/18, they look great but again, rear rim is 9.5" wide so 265's are right at home there.

[LIVEVIL]

Gotcha, I didn't pay attention to that rim size in the post.

[tripower]

Rim and aspect as stated above is important. You can run a bigger tire on a narrower rim but 1) you're not maximizing contact patch and 2) you may be out of spec for the rim causing issues.

I'm running into the issue with my old Goat. The 64-65s have small wheel wells and I want to run a 275/40 or 285/40 on the rear. That's no problem, but the American Torque Thrusts in 18" sizes are only available as 18x8 and 18x10 sized. Seeing as how a 10" wide rim is really 11" side to side, that may be too tight. So for now I'm stuck with the 255/45s on 18x8s on the rear. I'll have to measure to see if I can pull off 18x10s.

It sounds like our new Goats have the same issue with rather small "unmolested" wheel wells for shoving big tires in.

[LIVEVIL]

I was also wondering what the problem might be with the drop.

[LIVEVIL]

Well I am waiting to hear from my friend at the TireRack.

[djray77]

I am going with 245/40/18 all around. Thats the biggest size for a 18x8 rim. I have the eibach drop springs and the guy from shox.com told me if I dont rub now I will not rub with the drop.
Calculator from 1010tire, if you step up to 255 you need a min of 8.5 rim.

Stock Tire - 255/40R18 >Search Tires
Section Width: 10.03 in 255 mm
Rim Diameter: 18 in 457.2 mm
Rim Width Range: 8.5 - 10 in
Overall Diameter: 26.03 in 661.16 mm
Sidewall Height: 4.01 in 101.85 mm
Radius: 13.01 in 330.45 mm
Circumference: 81.77 in 2076.9 mm
Revs per Mile: 799.0

[LIVEVIL]

Hmm, I just spoke with my friend from the Rack and he said I'd be fine running the 255/35's. I hate the back and forth, I Just want a beefier look in the rear tires. I don't think 245's will get me there

[djray77]

I would like the wider tires out back also, but I dont want to have stability issues like MC2182 said, and I dont think you will have a good contact patch to the ground.

[LIVEVIL]

Damn, well I guess I could go with a set of 245's

[warhero]

I am going with 245/40/18 all around. Thats the biggest size for a 18x8 rim. I have the eibach drop springs and the guy from shox.com told me if I dont rub now I will not rub with the drop.
Calculator from 1010tire, if you step up to 255 you need a min of 8.5 rim.

Stock Tire - 255/40R18 >Search Tires
Section Width: 10.03 in 255 mm
Rim Diameter: 18 in 457.2 mm
Rim Width Range: 8.5 - 10 in
Overall Diameter: 26.03 in 661.16 mm
Sidewall Height: 4.01 in 101.85 mm
Radius: 13.01 in 330.45 mm
Circumference: 81.77 in 2076.9 mm
Revs per Mile: 799.0

When I was shopping for tires there was a manufacturer that listed 255 for 8 inch rims, I will try to find out which one. I have TOYO T1-R 245-40-18 on stock rims.

[warhero]

Onlinetires.com lists Nitto nt555 255-35-18's for 8-10 in rims

[LIVEVIL]

I just spoke with my friend again and he said 255 would need a 8.5 wheel. This is getting annoying.

[HotRodGuy]

Hmm, I just spoke with my friend from the Rack and he said I'd be fine running the 255/35's. I hate the back and forth, I Just want a beefier look in the rear tires. I don't think 245's will get me there


you want tire size for "looks"?

[Ryno]

Hmm, I just spoke with my friend from the Rack and he said I'd be fine running the 255/35's. I hate the back and forth, I Just want a beefier look in the rear tires. I don't think 245's will get me there

255 wont get you there either.

[LIVEVIL]

It was worth a shot. Yes, I wanted the rear tires to look wider, not really into whether or not anyone cares why. I make the payments on my car so.....

[JUDGEMENT]

It was worth a shot. Yes, I wanted the rear tires to look wider, not really into whether or not anyone cares why. I make the payments on my car so.....


My Old Man used to run 8in rims with 255's on his '69 427/400 horse corvette and he didn't have any problem with contact patches.

[LIVEVIL]

Thanks for letting me know. I am still undecided about what to do.

[rico750sxi]

My Old Man used to run 8in rims with 255's on his '69 427/400 horse corvette and he didn't have any problem with contact patches.

But was it an 18' rim? Less sidewall to play with on an 18" which limits the "wiggle" room you have for going wider.

[LIVEVIL]

Yeah I doubt it was an 18". I am not sure which way to go.

[JUDGEMENT]

Yeah I doubt it was an 18". I am not sure which way to go.

I just asked the guy at my local tire shop because I am thinking about getting an 18" rim and tire combo and he said 255's will fit with no problems.

[LIVEVIL]

I think they will fit OK, but my tirerack guy had me worried

[HotRodGuy]

I think they will fit OK, but my tirerack guy had me worried


Tire Rack is very very good at being conserivative and covering their ass as far as liability goes.

[LIVEVIL]

Ahh, that makes more sense now.